This invention relates to security rings for screw-threaded and snap-on closures for indicating whether a container has been opened.
Systems by which it is possible to see whether a pack has already been opened are well known. PCT Patent Application Publication No. WO 91/01925 relates to a closure for wide-necked containers comprising a cover with a security ring, the closure being mounted on the neck of the container. The principle of this tamper-proof closure system is based on the fact that, when the container is opened, the enlargement of the skirt of the closure cover deforms the security ring integral with the skirt which thus breaks at weakened points. This system offers a simple and safe way of telling whether a container has been opened. The disadvantage of this system is that it is designed for square Jars in which the security ring is broken by the deformation of the skirt of the cover. In the case of a round jar, there are no unlocking lugs on the neck of the container to deform the skirt of the cover. Accordingly, a solution based on a different principle has to be found.